JP5081180B2 - Traffic allocation calculation method, traffic allocation calculation device, session control device, and recording medium - Google Patents

Description

  In the C-plane (call control signal plane) that performs signaling such as connection control for a communication service via an IP (Internet Protocol) network, the present invention preferentially communicates some traffic when traffic is congested. It relates to traffic control technology to be secured.

  In a communication service via an IP network, calls (in this specification, meaning session start / change requests) concentrate on a specific session control device, and the session control device may be in a congestion state. As a method for resolving such traffic congestion, for example, Patent Document 1 discloses control of an outgoing call with a switchboard and a region where traffic communication becomes difficult due to concentration of incoming calls in a public telephone network as a ground (communication destination). In this case, the total number of calls (total number of calls) communicated to the ground is distributed to each exchange on the transmission side, and the number of outgoing calls exceeding this allocated value is regarded as a regulatory encounter at each exchange. It is disclosed that the distribution value is calculated by the number of connectable calls × the number of outgoing calls in the outgoing area / the total number of calls.

  Further, Patent Document 2 classifies calls that are added to a congestion device such as an exchange, periodically measures the number of calls for each class, and based on the actual values measured in the previous cycle. Thus, a method for determining the allocation of the number of calls to each class is disclosed. Therefore, the distribution value to each class is in line with the traffic trend.

  Further, in Patent Document 3, in the IP telephone system, the number of calls is monitored as a congestion detection method in which the function of a C-plane soft switch is brought into a stopped state due to the concentration of a large number of calls. The number is compared with a predetermined number of calls, and when the number of calls is larger than the predetermined number of calls, it is determined that there is congestion. Then, it is disclosed that a priority order for eliminating congestion is determined in advance for each terminal, and the higher the priority order, the higher the number of calls destined for that terminal (the number of calls per unit time) is set to be controlled. Yes.

  Patent Document 4 discloses that, in an IP network that provides a voice telephone service and a video telephone service at a fixed bandwidth ratio, user data is transmitted / received when congestion occurs where the voice telephone service bandwidth is insufficient. With respect to U-plane (user information transfer plane) resources, a method of allocating a part of a band for videophone service to a voice telephone service is disclosed.

Japanese Patent No. 2749659 Japanese Patent No. 3456406 Japanese Patent No. 3715604 JP 2007-336146 A

  However, with the methods disclosed in Patent Documents 1 to 4, it is difficult to preferentially secure a part of traffic in the IP network. In other words, the technology described in Patent Document 3 is controlled using call density uniformly without distinguishing outgoing traffic of a specific service and outgoing traffic of other services (for example, telephone and other services). Therefore, there is a problem that communication of some traffic cannot be secured preferentially. In Patent Document 1, as in Patent Document 3, a specific service and other services are not distinguished. Further, the technique described in Patent Document 4 only changes the allocation of the U-plane bandwidth, and does not ensure call communication in the C-plane. Furthermore, the technique described in Patent Document 2 performs control in accordance with a traffic trend and cannot preferentially secure communication of some traffic.

  Therefore, an object of the present invention is to provide a traffic control technique for preferentially securing communication of a part of traffic in a C-plane of an IP network in order to solve such a problem when traffic is congested. Objective.

In order to solve the above-mentioned problem, the invention according to claim 1 is characterized in that the session control device is congested when one of a plurality of session control devices used for C-plane (call control signal plane) of an IP network is congested. The number of calls that can be processed by the congestion session control apparatus among the session start / change requests (hereinafter referred to as session start / change requests) that request processing to the congestion session control apparatus. Assume that a certain number of connectable calls is X, and a call to the congestion session control apparatus is received for each class i defined based on information included in the call. Based on the traffic measurement periodically performed by the session control device 1 on the call control side, which is the session control device, the trough of the measurement cycle k−1. The number of outgoing calls click measurement data class belongs to the set G class calculated from _{i a i, k-1,} l ( class i, measuring period k-1, the session control unit l of the call regulation side) and Based on the number of outgoing calls a _{i, k−1, l} , the number of connectable calls X is allocated to the number of allocated calls x _{i, k} for each class i in the next measurement period k. Traffic distribution calculation for limiting the total number of calls accepted by the congestion session control device to the number of connectable calls X or less by restricting the number of calls added to the congestion session control device to x _{i, k} ,. In the traffic allocation calculation method used in the apparatus, the traffic allocation calculation device includes a calculation unit and a storage unit that stores the definition of the class, and the calculation unit sets the class i read from the storage unit as congestion. Priority is given to communication Priority allocation class and allocated to the non-priority allocation class that does not ensure the communication in preference to during congestion, also reads an initial allocation call number s _i of predetermined value from the storage unit for each class i, right after congestion detection for When the measurement cycle k is k = 0 and the measurement cycle k> 1, the function g: (0, ∞) → (0, ∞) satisfying the function g (z) ≦ 1 / z is used. allocation call number x _i of the class i of each priority allocation class _{k, k,} a _{· x i, k, · =} g (R p) · MAX {s i, a i, k-1, ·} ·· formula (1)
And the number of allocated calls x _{i, k, ·} of class i of each non-priority allocation class of measurement period k is _expressed as x _{i, k, ·} = (a _{i, k−1, //} Σ _{j∈non-priority allocation A set of classes} a _{j, k-1, ·} ) · (1−g (R _p ) · R _p ) · X
..Formula (2)
It is calculated as follows.
Where R _p = (Σ _{i∈priority allocation class set} MAX {s _i , a _{i, k−1,} }) / X, s _· = X, a _{i, k−1,} and x _{i, k ,} the midpoint _of, "-" is a dot notation, represents the sum of all of the outgoing call restriction side session control device l.

According to such a configuration, in the measurement cycle k> 1, as indicated by MAX {s _i , a _{i, k−1,} ... In Equation (1), the number of initial allocated calls s _i or the previous measurement cycle k− Since the larger one of the number of outgoing calls a _{i, k-1,} ... At ₁ is selected, the priority call class always allocates the call that matches the trend of the number of outgoing calls while ensuring the initial number of calls. The number can be secured. For this reason, communication of a part of the traffic (priority allocation class) can be secured with priority. Further, the number of calls allocated to the non-priority distribution class can be determined so as not to exceed the number of calls X that can be connected according to the equation (2).

According to a second aspect of the present invention, in the traffic control method according to the first aspect, when the measurement period k> 1, the calculation unit distributes the call control side session control device l to the measurement period. The number of allocated calls x _{i, k, l} of class i of _k
x _{i, k, l} = (a _{i, k-1, l} / a _{i, k-1,.} ) x _{i, k,} ... (3)
It is calculated as follows.

  According to such a configuration, in the measurement cycle k> 1, as shown in the equation (3), the number of allocated calls of each class of the session control device on each call restriction side in the measurement cycle k is set to the previous measurement cycle k−. 1 is determined based on the number of outgoing calls. Therefore, it is possible to determine the number of allocated calls of each class of the session control device on each call restriction side according to the trend of the number of outgoing calls.

According to a third aspect of the present invention, in the traffic control method according to the first or second aspect, the calculation unit reads the initial allocated call number s _i from the storage unit, and the measurement cycle k = 1 The number of calls allocated to class i x _{i, k} ,
xi _{, k} ,. = s _i .. Formula (4)
It is characterized by.
However, s _· = X.

  According to such a configuration, the number of class i allocated calls at the time of the measurement cycle k = 1 can be calculated using the formula (1) or the formula (2) because there is no number of outgoing calls of the measurement cycle k−1. There wasn't. However, according to the equation (4), it is possible to set an appropriate number of initial allocated calls (not over-regulated) at the time of the measurement cycle k = 1. Therefore, the trend of the number of allocated calls can be clarified from the time when the measurement cycle k = 1.

Invention of Claim 4 is the traffic control method as described in any one of Claim 1 thru | or 3, Comprising: When the said calculating part is measurement period k = 1, it is normal traffic measurement. Based on the number of normal outgoing calls, the number of normal outgoing calls of class i belonging to the class set G calculated from the data is u _{i, l} (class i, session control device 1 on the outgoing call restriction side). The number of allocated calls x _{i, k, l} of class i in the measurement period k, which is allocated to the session control device l on the call control side,
x _{i, k, l} = (u _{i, l} / u _{i ,.} ) x _{i, k,} ... (5)
It is calculated as follows.

  According to such a configuration, since the number of allocated calls distributed to the session control apparatus 1 on the call control side at the time of the measurement cycle k = 1 does not include the number of outgoing calls of the measurement cycle k−1, the expression (3) is obtained. It was not possible to calculate using. However, according to the equation (5), at the time of the measurement cycle k = 1, it is possible to set the number of allocated calls based on the actual number of normal outgoing calls.

  A fifth aspect of the present invention is the traffic control method according to any one of the first to fourth aspects, wherein the calculation unit includes SIP (Session Initiation Protocol), SIMPLE ( The class is defined by a combination of various methods of SIP for Instant Messaging and Presence Leveraging Extensions), parameters of SDP (Session Description Protocol), calling subscriber classification, and emergency call classification. To do.

  With this configuration, it is possible to easily define a class even in an IP network.

According to the sixth aspect of the present invention, when a congestion occurs in any of a plurality of session control devices used for C-plane (call control signal plane) of the IP network, the congestion session control device that is the congested session control device is processed. The number of connectable calls, which is the number of calls that can be processed by the congestion session control device, is X among session start / change requests (hereinafter referred to as session start / change requests). A call that is the session control device that receives a call directed to the congestion session control device for each class i defined based on information included in the call. Based on the traffic measurement periodically performed in the session controller 1 on the restricting side, it is calculated from the traffic measurement data of the measurement cycle k−1. The number of outgoing calls a _i of class i belonging to the set G class _{that, k-1, l} (class i, measuring period k-1, the session control unit l of the call regulation side), and the outgoing call number a _{i , k-1, l} , the number of connectable calls X is distributed to the allocated number of calls x _{i, k,} ... for each class i in the next measurement period k and added to the congestion session control device of class i. A traffic allocation calculation device that restricts the total number of calls accepted by the congestion session control device to the number of connectable calls X or less by regulating the number of calls to be less than or equal to x _{i, k} ,. The traffic measurement data is received from the session control device on the call regulation side, accumulated, and the number of outgoing calls is notified to the following distribution value determination unit, and the distribution call number that is the calculation result of the distribution value determination unit is determined. Notify the session control device on the call restriction side 6. The traffic measurement data is received from a constant data management unit and the measurement data management unit, and based on the traffic measurement data, the number of allocated calls is calculated by the traffic allocation calculation method according to any one of claims 1 to 5. And a distribution value determining unit.

According to such a configuration, as in the first to fifth aspects, in the measurement cycle k> 1, as shown by MAX {s _i , a _{i, k−1} ,. Since the larger one of the number of allocated calls s _i or the number of outgoing calls a _{i, k-1, · in} the previous measurement period k−1 is selected, the initial allocated number of calls is always secured for the priority allocation class. However, it is possible to secure the number of allocated calls that matches the trend of the number of outgoing calls. Therefore, communication of a part of the traffic (priority allocation class) can be secured with priority. Further, the number of calls allocated to the non-priority distribution class can be determined so as not to exceed the number of calls X that can be connected according to the equation (2). Further, in the measurement cycle k> 1, as shown in the equation (3), the number of allocated calls of each class of the session control device on each call restriction side in the measurement cycle k is set to the outgoing call of the previous measurement cycle k−1. Determine based on the number. Therefore, it is possible to determine the number of allocated calls of each class of the session control device on each call restriction side according to the trend of the number of outgoing calls. Also in the IP network, it is possible to easily define a class.

According to a seventh aspect of the present invention, there is provided the session control apparatus on the call restriction side for determining connection of a call based on the number of allocated calls x _{i, k, l} acquired from the traffic distribution calculation apparatus according to the sixth aspect. The session control device includes: a call restriction unit that controls call restriction; and a storage unit that stores a definition of a class defined based on information included in a call that is a session start / change request. The call restriction unit determines whether to ensure communication of class i calls stored in the storage unit or to meet a restriction based on the acquired number of allocated calls x _{i, k, l.} As a result, when the call of the priority allocation class becomes a regulation encounter, reconnection is performed in order from the lowest class of the priority of the non-priority allocation class to determine whether or not communication is possible. Through a class that is determined to be able to communicate And executes a retry to communicate with priority since calling a.

  According to such a configuration, even if a call of a priority allocation class becomes a regulation encounter, a communication of a priority allocation class that has encountered the regulation is secured through a class that can ensure communication in a non-priority allocation class. can do. Therefore, it is possible to secure communication of a part of the calls (priority allocation class) with priority. In addition, when reconnection is performed in the non-priority distribution class, it is possible to leave the band of the higher priority class by executing from the lower priority order.

A seventh aspect of the present invention is the session control apparatus according to the seventh aspect, wherein the call control side session control apparatus measures the time and the number of allocated calls received from the traffic distribution calculation apparatus. And a means for performing call restriction using a call density value that is the number of calls per predetermined unit time, and processing in an unregulated class that does not perform call restriction as described in (81), (82) and (83) are performed in order,
(81) receiving an instruction for calculating a call density value for all classes from the traffic allocation calculation device;
(82) The total number of outgoing calls of all classes including the unregulated class is added from an initial value of 0,
(83) Determine whether the total number of outgoing calls is less than the call density value for all classes,
If the total number of outgoing calls is less than the call density value for all classes, return to (82) again, and if the total number of outgoing calls is not less than the call density values for all classes, it is not an unregulated class. If the unit time of call density is over for all classes of the above, and if the unit time of the call density ends, the process returns to (82) to execute the processing in order, and when the measurement period ends, Returning to (81), the processing is executed in order.

  According to this configuration, the total number of outgoing calls for all classes including the unregulated class is calculated by the processes of (82) and (83), and the number of layer outgoing calls is limited to the call density value for all classes. Therefore, the possibility that the number of connections to the congestion session control device exceeds the number of connectable calls X can be minimized.

  According to a ninth aspect of the present invention, in the session control device according to the seventh or eighth aspect, the session control device on the call-restricting side determines the parameter of the SDP parameter included in the received call. When there are a plurality of parameter values, an SDP parameter representative value determination map for associating one representative value with the plurality of parameter values and a class defined based on the SDP parameters are stored. Which class is applicable is determined using the SDP parameter representative value determination map.

  According to such a configuration, when there are a plurality of parameter values for the SDP parameter included in the call, a mapping (SDP parameter representative value determination) is made to correspond to the plurality of parameter values. Mapping) and classes defined based on SDP parameters, it is possible to easily determine which class the received call corresponds to.

  The invention according to claim 10 is a computer-readable recording medium in which a traffic allocation calculation program for executing the traffic allocation calculation method according to any one of claims 1 to 5 is recorded. It is characterized by. With this configuration, a computer (traffic distribution calculation device) equipped with this recording medium can realize each function based on a program recorded on this recording medium.

  The invention described in claim 11 is a computer-readable recording medium, and a session for causing the computer to function as a session control device on the call-restricting side according to any one of claims 7 to 9. A control program is recorded. By being configured in this way, a computer (calling-controlling session control device) equipped with this recording medium can realize each function based on a program recorded on this recording medium.

  According to the present invention, it is possible to provide a traffic control technique for preferentially securing communication of a part of traffic in a C-plane of an IP network when traffic is congested.

It is a figure which shows the structural example in this embodiment. It is a figure which shows the outline | summary of this embodiment. It is a figure which shows the calculation process of the number of allocation calls. It is a figure which shows the specific example of the function g (z). (A) is a figure which shows the function of a traffic allocation calculation apparatus, (b) is a figure which shows the function of a call control session control apparatus, (c) is a figure which shows the function of a congestion session control apparatus. It is a figure which shows the flow of the information between a call control session control apparatus and a traffic allocation calculation apparatus. FIG. 10 is a diagram showing a flow of processing for retrying for communication of a call when the call becomes a restriction encounter in the priority allocation class. It is a figure which shows the process in an unregulated class. It is a figure which shows the specific example of the calculation process of the number of allocation calls. It is a figure which shows an example of the process which identifies applicable class from the protocol header of the session start / change request in this embodiment. It is a figure which shows an example of a class definition. It is a figure which shows the structure of the traffic control system in a modification.

  Next, a mode for carrying out the present invention (hereinafter referred to as “the present embodiment”) will be described in detail with reference to the drawings as appropriate.

  A configuration example and an outline in the present embodiment will be described with reference to FIGS. 1 and 2. The target devices in this embodiment are the traffic allocation calculation device 10 and the session control device 40 shown in FIG. The C-plane includes a plurality of session control devices 40A, 40B, and 40C (40). Then, the session control device 40 receives the call from the terminal 90 and transmits it to the destination. Note that the solid line in FIG. 1 does not represent a physical connection, but represents that information can be transmitted and received. The traffic allocation calculation device 10 determines the number of calls for ensuring communication of the call for the call that arrives at the session control device 40 (in this specification, means a session start / change request). It is a device that instructs to. Then, the session control device 40 receives a call from the terminal 90 and performs control to transmit a packet to the session control device 40 that is a destination of the call based on an instruction from the traffic distribution calculation device 10. . Although only three session control devices 40 are shown in FIG. 1, the present invention is not limited to this.

  In the configuration of FIG. 1, for example, it is assumed that calls are concentrated from the session control device 40 of another network or the own network and congestion occurs in the session control device 40C. In this case, the session control device 40C is referred to as a congestion session control device. Further, the session control device 40 (40A, 40B in FIG. 1) that controls outgoing calls to the congestion session control device is referred to as a call restriction session control device. In the following description, the congestion session control device and the call restriction session control device are used.

  Next, an outline of a processing flow for preferentially securing communication of a part of traffic in the present embodiment will be described with reference to FIG. First, in congestion control, the traffic communication of a specific service (for example, a voice telephone service) is preferentially secured. Therefore, class i is defined for outgoing calls. Here, an example of class definition will be briefly described with reference to FIG. Class i is classified by, for example, calling subscriber classification (general, emergency, etc.), and further, as a call type, SIP (Session Initiation Protocol) used in the IP network, SIMPLE (SIP for Instant Messaging and Presence Leveraging Extensions) ), Various methods, SDP (Session Description Protocol) parameters, and the like. Then, for each class, a priority distribution class that secures communication preferentially during congestion or a non-priority distribution class that is non-prioritized is determined, and a priority order for each class is determined in advance. In FIG. 2, the range with dots is the priority allocation class.

When the traffic allocation calculation device 10 receives a call restriction request from a congestion session control device, the traffic session calculation device 10 can connect to the congestion session control device X and the call restriction session control device class i is acquired from the call restriction session control device l. Using the number of outgoing calls a _{i, k-1, l,} etc., the class i, the measurement period k, and the number of allocated calls x _{i, k, l} of the call control session control device _l are calculated, and the calculated distribution The number of calls x _{i, k, l} is transmitted. Then, the call restriction session control device l determines whether to ensure the communication of the call of class i or to meet the restriction based on the received distributed call number x _{i, k, l} . The measurement period k is a period for identifying periodically performed traffic measurement. The connectable call number X is the number of calls that can be connected to the call arriving from the call restriction session control device l in the own network, and is an input means (keyboard or the like) not shown by the operator of the traffic allocation calculation device 10. ) Or the notification from the session control device 40 or the like, the traffic allocation calculation device 10 has acquired in advance.

  Then, the call control session control device l performs reconnection in order from the lowest priority of the non-priority allocation class when the call of the priority allocation class becomes a control encounter, and finally, Retry to prioritize communication for outgoing calls. This makes it possible to ensure the communication of some traffic preferentially during traffic congestion.

Next, details of processing for preferentially securing communication of some traffic in the present embodiment will be described.
First, variables used in this process will be described.

X: Number of calls that can be connected to the congestion session control device G: {i | i is class}
L: {l | l is a call control session control device}
P: {p | p is a priority allocation class}
x _{i, k, l} : Class i, measurement period k, number of allocated calls of call control session control apparatus l a _{i, k, l} : Class i, measurement period k, number of outgoing calls of call control session control apparatus l u _{i, l} : Number of normal outgoing calls of class i, call control session control device l

In the following description, the notation is expressed using dot notation. For example, the total sum of the number of calls allocated to all call restriction session control apparatuses l is expressed as x _{i, k,.} That is, x _{i, k ,.} = Σ _l∈L x _{i, k, l} . Further, the number of connectable calls X differs depending on the session control device 40 (see FIG. 1) due to the difference in the installed capacity of various hardware and the functions provided such as provided services. In order to take up and explain, X is described.

≪Call distribution policy≫
In order to determine the class i, the measurement period k, and the number of allocated calls x _{i, k, l} of the call control session control device l, first, the policy of the number of calls allocation is determined. The policy is shown below.
(1) The number of connectable calls X is allocated to the priority allocation class and the non-priority allocation class, and further allocated to each call restriction session control apparatus l. The allocation order is basically the priority allocation class first and the non-priority allocation class later.
(2) In the call number distribution process, data is considered in the following order.
・ First order Number of calls set in class i that should secure communication preferentially ・ Second order Traffic measurement data measured in the previous measurement cycle k−1 ・ Third order Normal traffic measurement data For example, the “number of calls set in class i for which communication should be preferentially secured” of the first rank is, for example, the status of functions necessary for each class of the congestion session control device (the session control device Whether it is a device of the type to be accommodated or a device dedicated to application installation, dedicated to application connection of other devices, whether it is a device containing a video server, and if it is a device containing a video server The number of video servers that are connected at the same time, etc.), or considering operational policies.

≪Distributed call count calculation process≫
The distributed call count calculation process will be described with reference to FIG. FIG. 3 shows (1) << number of connectable calls X to class i allocated calls x _{i, k} for each of the measurement period k = 1 and measurement period k> 1 for the priority distribution class and the non-priority distribution class. _. the calculation », (2)« class i distributed call number x _{i of, k,.} allocation number of calls call regulation session control device l from x _{i, k,} in the order of calculation _{»l of} allocation call number x _This represents calculating _{i, k, l} . The measurement cycle k = 0 is a measurement cycle immediately after congestion detection.

Since the predetermined calculation process using the traffic data of the previous measurement cycle k-1 cannot be performed at the measurement cycle k = 0, the initial allocated call number s _i is stored (set) for each class i in advance. . However, the total number of initial allocated calls s _i is equal to the number of connectable calls X (do not exceed X). That is, s. = X.
In addition, for any pεP, in order to secure communication with priority, the number of initial allocated calls s _i is set to the number of calls that need to ensure communication even after the next measurement period k = 1. Keep it.

Next, a call number distribution calculation process in the priority distribution class will be described (see FIG. 3).
In the measuring period k = 1, as shown in (1) in FIG. 3, the distribution number of calls x _i for class _{i, k,.} = The initial allocation call number s _i. Then, in FIG. 3, as shown in (2), distributed call number x _i of the call regulation session control device l priority allocation _{class, k, l} is normal when outgoing calls number u _{i, l of} the formula (6) Calculated by applying to
Number of allocated calls x _{i, k, l} of call control session control device l of priority allocation class
= (U _{i, l} / u _{i ,.} ) X _{i, k,} ... (6)
It should be noted that the actual situation can be reflected by determining the number of allocated calls x _{i, k, l based} on the number of normal outgoing calls, which is the actual value of outgoing calls, using Equation (6).

In the measurement cycle k> 1, the number of allocated calls x _{i, k} ,. Of the priority allocation class applies the number of outgoing calls a _{i, k−1,} of class i in the previous measurement cycle k−1 to equation (7). Is calculated. The allocation call number x _i of the call regulation session control device l priority allocation _{class, k, l} are originating call number a _i of class i in the measurement period _{k-1, k-1,} . Eq (8) Calculated by applying to
Number of calls assigned to priority allocation class x _{i, k,.} = G (R _p ) · MAX {s _i , a _{i, k−1} ,.
Number of allocated calls x _{i, k, l} of call control session control device l of priority allocation class
= (A _{i, k-1, l} / a _{i, k-1,.} ) X _{i, k,} ... (8)
_{However, R p = (Σ j∈P MAX} {s j, a j, k-1,.}) / X, is _{g (R p) ≦ α /} R p (0 <α ≦ 1).
Here, the function g takes into consideration that the total number of allocated calls x. _{, K,} ... Details of this function g will be described later.

In Equation (7), either MAX {s _i , a _{i, k−1,} ..., Either initially allocated call number s _i or outgoing call number a _{i, k−1} ,. Since the larger one is selected, it is possible to ensure the number of allocated calls that matches the trend of the number of outgoing calls while always ensuring the initial number of allocated calls s _i .
In equation (8), all outgoing calls number a _{i, k-1,} originating number of calls for each class i for. A _{i, k-1,} at a rate of _l, total allocation call number x _i of the priority allocation _{class, k ,} . Can be distributed according to the trend of the number of outgoing calls.

Next, the call number distribution calculation process in the non-priority distribution class will be described below.
In the measurement cycle k = 1, as shown in (1) of FIG. 3, the number of allocated calls x _{i, k} . = Initial allocated number of calls s _{i of} class _i is set. Then, as shown in (2) in FIG. 3, the distribution number of calls x _i of call regulation session control device l of the non-priority allocation _{class, k, l} is normal when outgoing calls number u _{i, l of} the formula (9 ) To calculate.
Number of allocated calls x _{i, k, l} of call control session controller l of non-priority allocation class
= (U _{i, l} / u _{i ,.} ) X _{i, k,} ... (9)

In the measurement cycle k> 1, the number of allocated calls x _{i, k} ,. Of the non-priority allocation class of class i is expressed by the following equation ( ₁₎ . It is calculated by applying to 10). The allocation call number x _i of the call regulation session control device l of the non-priority allocation _{class, k, l} are originating call number a _i of class i in the measurement period _{k-1, k-1,} . Eq (11 ) To calculate.
Number of allocated calls x _{i, k,.}
= (A _{i, k-1,} ./Σ _j∈GP a _{j, k-1 ,.} ) · (1-g (R _p ) · R _p ) · X
..Formula (10)
Number of allocated calls x _{i, k, l} of call control session controller l of non-priority allocation class
= (A _{i, k-1, l} / a _{i, k-1,.} ) X _{i, k,} ... (11)

<< Function g >>
Here, the function g will be described. At least the total number of calls allocated to the priority allocation class must be less than or equal to the number of connectable calls X. here,
R _p ≡ (Σ _j∈P MAX {s _j , a _{j, k-1 ,.} }) / X (12)
In other words, when R _p > 1, the total number of allocated calls in the priority allocation class exceeds X. Therefore, using the function g: (0, ∞) → (0, ∞) where g (z) ≦ 1 / z,
x _{i, k,.} = g (R _p ) · MAX {s _i , a _{i, k−1,} }} (13)
And allocate. When the total sum for class iεP on both sides of equation (13) is calculated, the total number of calls allocated to the priority allocation class is as shown in equation (14).
Σ _j∈P x _{j, k ,.} = G (R _p ) · Σ _j∈P MAX {s _j , a _{j, k-1 ,.} } = G (R _p ) · R _p · X
..Formula (14)
Therefore, (Σ _i ∈ _P x _{i, k ,.} ) / X = g (R _p ) · R _p ≦ 1, and by this allocation method, the total number of allocated calls in the priority allocation class becomes the number of connectable calls X Never exceed.

A specific example of the function g (z) will be described with reference to FIG. The horizontal axis of FIG. 4 is the variable z in the function g (z) = α / z, and the vertical axis is the value of g (z). Α is defined as 0 <α ≦ 1, and g (z) = 1 is set in the range of 0 <z ≦ α, and g (z) = α / z is set in the range of α <z. For example, if α = 1, g (z) can always be 1 in the range of 0 <z ≦ 1, and the number of allocated calls x _{i, k} ,. {s _i , a _{i, k−1,.}

Next, functions of the traffic distribution calculation device 10, the call restriction session control device l, and the congestion session control device 50 will be described with reference to FIG.
The traffic allocation calculation device 10 shown in FIG. 5A is a device that calculates the number of allocated calls x _{i, k, l} based on the traffic measurement data acquired in the measurement cycle k−1. 20, a measurement data management unit 25, and a session control device information storage unit 30. The measurement data management unit 25 acquires traffic measurement data from the call restriction session control device l and notifies the distribution value determination unit 20 of them. Next, the distribution value determining unit 20 determines the number of allocated calls x _{i, k, l} based on the traffic measurement data notified from the measurement data management unit 25. Then, the measurement data management unit 25 notifies the call restriction session device l of the number of allocated calls x _{i, k, l} calculated by the distribution value determining unit 20.

As a function, the distribution value determining unit 20 includes a class definition accumulating unit 22 for storing the class definition in the control parameter management unit 21 for defining the class _, and calculates the number of allocated calls x _{i, k, l} . A calculation unit 23 that performs calculation is provided. The calculation unit 23 includes a CPU (Central Processing Unit) (not shown) and a main memory (not shown) that is used by the CPU for calculation processing and the like. An application program is developed in the main memory, and the CPU executes it. These functions are realized. The class definition will be described later.

The measurement data management unit 25 functions as a measurement data storage unit 26 that stores traffic measurement data acquired from the call control session control device l and the number of allocated calls x _{i, k, l} calculated by the distribution value determination unit 20. Is provided to the call control session device l.

  For each session control device 40 (see FIG. 1), the session control device information storage unit 30 stores the number of initial allocation calls by class 31 that stores the number of initial allocation calls of class i, and the number of calls that can be connected during congestion. , A normal class i incoming traffic data accumulating unit 33 for storing class i incoming traffic measurement data, and a normal class i outgoing traffic measurement data for storing class i outgoing traffic measurement data. An outgoing traffic data storage unit 34 for each time class is provided.

  Next, the call control session control device 1 shown in FIG. 5B includes a call control unit 41, a data measurement unit 42, an SDP parameter representative value determination mapping storage unit 43, a priority setting storage unit 44, and a class definition. A storage unit 45 is provided. The outgoing call restriction unit 41 restricts outgoing calls to the congestion session control device based on the number of distributed calls calculated by the traffic distribution calculation device 10. The data measuring unit 42 measures outgoing traffic measurement data and incoming traffic measurement data. The SDP parameter representative value determination mapping storage unit 43 associates one representative value with a plurality of parameter values when there are a plurality of parameter values for some of the SDP parameters included in the call. The mapping (SDP parameter representative value determination mapping) is stored. This SDP parameter representative value determination mapping will be described later. The priority setting accumulation unit 44, when a call of the priority allocation class becomes a restriction encounter, prioritizes the non-priority distribution class when performing a retry to ensure communication of the call that has encountered the restriction Remember the rank. The class definition accumulation unit 45 stores the same class definition as the class definition stored in the class definition accumulation unit 22 of the traffic distribution calculation device 10. The stored contents of the class definitions stored in the class definition storage unit 45 are acquired by operating the input means (keyboard or the like) (not shown) by the operator of the call restriction session control device l or by notification from the traffic distribution calculation device 10. Is done.

  The congestion session control device 50 illustrated in FIG. 5C includes at least a call restriction request unit 51 that transmits a call restriction request to the traffic distribution calculation device 10 as a function.

Next, the flow of information between the call restriction session control device l and the traffic allocation calculation device 10 in this embodiment will be described with reference to FIG. 6 (see FIGS. 1 and 5 as appropriate).
First, the traffic allocation calculation device 10 receives a call restriction request from the congestion session control device 50 (step S601). Next, the traffic allocation calculation device 10 reads the connectable call count X of the congestion session control device 50 that has transmitted the call restriction request from the processable call count storage unit 32 (step S602). Then, the call restriction session control device l notifies the traffic allocation calculation device 10 of the number of outgoing calls a _{i, k−1, l} in the measurement cycle k−1 (step S603).

The traffic allocation calculating device 10 uses the number of outgoing calls a _{i, k−1, of} the measurement period k−1 and the number of connectable calls X already acquired, which is notified from the call control session control device l. Thus, the number of allocated calls x _{i, k, l} in the next measurement period k is calculated (step S604). The traffic allocation calculation device 10 notifies the call control session control device l of a connection control instruction signal indicating the calculated allocation call number x _{i, k, l} (step S605). The call restriction session control apparatus l receives the connection control instruction signal (step S606). Then, the call restriction session control device l determines the call density value based on the allocated call number x _{i, k, l} indicated in the received connection control instruction signal and the class definition stored in the class definition storage unit 45. Take control. Although not shown in FIG. 6, the congestion session restriction device 50 also has the same number of allocated calls x _{i, k,} indicated in the received connection control instruction signal as the call restriction session control device l shown in FIG. 6. _The call density value control is performed based on the class definitions stored in the class definition storage unit 52. Note that the call density value is the number of calls per unit time as described above.

Next, the flow of retrying the call density control for ensuring the communication of a call when the call becomes a restriction encounter in the priority allocation class will be described with reference to FIG. 7 (see FIG. 5 as appropriate). ). The process shown in FIG. 7 is executed by the call restriction session control apparatus l.
First, the call restriction session control apparatus l sets the priority order of the non-priority distribution class. Here, it is assumed that, as the number of non-priority allocation classes is μ and the numerical value of the priority order m is larger, the priority is lower (prone to encounter a regulation). Information regarding the priority order is stored in the wired order setting accumulation unit 44.

First, the priority m of the non-priority distribution class is set to μ (step S701). That is, m = μ. Then, the retry is started from the lowest priority. Next, the call restriction unit 41 reattempts call density control in the same way as a call in a non-priority distribution class with priority m for a call that encounters restriction (step S702).
If communication is established (Yes in step S703), the number of calls communicated per unit time of the non-priority distribution class with priority m is incremented by 1 (step S706).
If communication is not established (No in step S703), it is determined whether m = 1 (step S704).
If m = 1 is not satisfied (No in step S704), m = m−1 is set, and the priority is moved to the next higher class (step S707), and the process returns to step S702. If m = 1 (Yes in step S704), this call is regarded as a restriction encounter (step S705).

≪Processing in unregulated class≫
The unregulated class is one way of thinking that some classes communicate with priority. For example, the unregulated class is a class that does not execute the congestion control process in order to ensure communication, such as a telephone call from an emergency response organization in the government. However, since the unregulated class is not regulated, it is assumed that the required outgoing calls are larger than the set number of calls. In such a case, it is necessary to suppress the number of connectable calls X of the congestion session control device so as not to exceed. The unregulated class may be a class different from the priority allocation class or may be included in the priority allocation class.

The process in the unregulated class will be described with reference to FIG. 8 (see FIG. 5 as appropriate). 8 is executed by the call restriction session control apparatus l.
First, an instruction for calculating call density values for all classes is received from the session control device instruction unit 27 (step S801). Then, the call restriction unit 41 adds the total number of outgoing calls of all classes including the unregulated class from the initial value 0 (step S802). Next, the call restriction unit 41 determines whether the calculated total number of outgoing calls is less than the call density value for all classes (step S803).

  If the calculated total number of outgoing calls is less than the call density value for all classes (Yes in step S803), the process returns to step S802. If the calculated total number of outgoing calls is not less than the call density value for all classes (No in step S803), the outgoing call restriction unit 41 sets outgoing calls as restricted encounters for all classes other than the unregulated class. (Step S804).

  Next, it is determined whether or not the unit time of call density has ended (step S805). If the call density unit time has expired (Yes in step S805), the process returns to step S802. If the call density unit time has not ended (No in step S805), it is determined whether the measurement cycle has ended (step S806). If the measurement cycle has ended (Yes in step S806), the process returns to step S801. If the measurement cycle has not ended (No in step S806), the process returns to step S805. Note that the order of step S805 and step S806 may be either. In this way, even if an unregulated class is provided, it is possible to control traffic so that the number of calls required per unit time does not exceed the connectable number of calls X.

≪Specific example of calculation process of number of allocated calls≫
Here, a specific example of the distribution call number calculation process in the measurement cycle k = 1 shown in FIG. 3 will be described with reference to FIG. As shown in FIG. 9, as the class-by-class allocation values at the time of congestion, the class A initial allocation number of calls is 3000 calls / min and the class B initial allocation call count is 7000 calls / min. The number of normal outgoing calls u _{i, 1 of} l (l = 1) is 2700 calls / minute for class A and 300 calls / minute for class B, and call control session control device l (l = 2) Assume that the number of normal outgoing calls u _{i, 2} is 400 calls / minute for class A and 4000 calls / minute for class B.
In this case, for each class i, among the call restriction session control devices l, the call distribution restriction session control device with respect to the sum of the normally distributed call numbers u _{i, l} for each class i is assigned to the initial distribution call number s _i. The number of allocated calls is determined by the ratio of the number of normal outgoing calls u _{i, l} of _l . That is, in the call control session control device 1 (l = 1), the class A allocated call count is calculated by multiplying the initial allocated call count 3000 calls / min by 2700 / (2700 + 400). Similarly, the class B allocated call number of the call control session control device l (l = 1) is calculated by multiplying the initial allocated call number 7000 calls / min by 300 / (300 + 4000). The same applies to the call restriction session control device l (l = 2).

≪Class definition≫
Next, the definition of the communication service class in the present embodiment will be described.
That is, in the existing public telephone network, classification is performed using call types and routes as described in Patent Document 2, but various types of SIP and SIMPLE included in the outgoing call targeted in this embodiment are used. The parameters are different from those of the method and SDP. That is, in the present embodiment, it is necessary to define a class based on a new index.

  The definition of the set G based on the class i will be described below. The set G is defined by a target method set Θ, a target SDP parameter classification set Λ, a calling subscriber classification set Ω, and an emergency call classification set Δ. The set G is defined by the following (Procedure 1) to (Procedure 5) performed by the traffic distribution calculation device user. The defined result is accumulated in the class definition accumulation unit 22 (see FIG. 5A) and the class definition accumulation unit 45 (see FIG. 5B). In the following, first, Θ ′, Λ ′, Ω, and Δ are defined.

All SIP, SIMPLE method partition set Θ ′: = {θ ′ | θ ′ is a SIP, SIMPLE method. However, the INVITE other than the Initial INVITE and the Initial INVITE are different sources. }
Θ '= {INVITE excluding Initial INVITE, Initial INVITE, ACK, CANCEL, BYE, REGISTER, OPTIONS, REFER, INFO, SUBSCRIBE, NOTIFY, PRACK, UPDATE, MESSAGE} (IETF-REC 2976,3261,3262,3265,3311 , 3428, 3578, 4488)

SDP parameter partition set Λ ′: = {φ, λ ′ _i | i∈H; H is a set of parameters defined in SDP. Φ is an empty set. }
That is, Λ ′ is a set based on φ and λ ′ _i . Note that λ ′ _i : = (name of parameter of i, value range q ′ _{i of} parameter _i ). For example, when the parameter name of i is bandwidth, its value range q ′ _i is [0, ∞).

Ω: = {ω | ω is a calling subscriber category}.
For example, if the calling subscriber category is 3 categories, it is as follows.
Ω = {first outgoing subscriber category, second outgoing subscriber category, third outgoing subscriber category}

Δ: = {δ | δ is an emergency call classification}.
For example, if the type of emergency call is fire, ambulance, maritime security, it will be as follows.
Δ = {other than fire, emergency, maritime security, emergency calls}

  Next, (Procedure 1) to (Procedure 5) for defining the class set G are shown below. These procedures are performed by an operator who operates the traffic distribution calculation device 10.

(Procedure 1)
A target method set Θ and an SDP parameter classification set Λ ″ are selected.
First, a target method set Θ = {θ | θ∈Θ ′ and θ is a method used for session start / change for traffic control} is selected from all SIP and SIMPLE method partition sets Θ ′.
Similarly, from the SDP parameter classification set Λ ′, the name of the parameter necessary for selecting the traffic to be controlled and the value range of the parameter are selected. Specifically, H ′ that is H′⊆H is defined as a set of SDP parameters used to distinguish traffic in traffic control. 'Of _j, excluding the unnecessary range in providing communication services q' range q selecting 'a _{j q''j⊆q' j} . A set based on λ ″ _j : = (j parameter name, q ″ _j ) and the empty set φ is Λ ″: = {φ, λ ″ _j | j∈H ′}. .

Here, four specific examples of λ ″ _j are shown.
(Example 1) When text is not selected from the range of the SDP parameter MediaType in an unnecessary range (see IETF-RFC 4566, 4856)
λ '' _m = (media_type, (audio, video, application, message, audio / DV14, audio / G722, audio / G723, audio / G726-16, audio / G726-24, audio / G726-32, audio / G726 -40, audio / G728, audio / G729, audio / G729D, audio / G729E, audio / GSM, audio / GSM-EFR, audio / L8, audio / L16, audio / LPC, audio / PCMA, audio / PCMU, audio / VDVI, video / nv})

(Example 2) When only recvonly, sendrecv, and sendonly are selected from the range of SDP parameter attributes (inactive, rtpmap, etc. are not selected in the unnecessary range) (see IETF-RFC 4566)
λ '' _a = (attributes, {recvonly, sendrecv, sendonly})
(Example 3) When band [0, ∞) (kb / s) is selected from the range of SDP parameter bandwidth (all range is selected) (see IETF-RFC 4566)
λ '' _b = (bandwidth, [0, ∞)) (kb / s)
(Example 4) When {0,1,2, ..., 126,127} is selected from the range of SDP parameter Rtp payload type (all ranges are selected) (http://www.iana.org/assignments/rtp- parameters)
λ '' _r = (Rtp_payload_type, {0,1,2, ..., 126,127})

(Procedure 2)
As in the case of λ ″ _b described above, when the range is non-addition, or when the range can be added, the number of elements in the range is large.
q ″ _j is divided into direct sums so that the range of q ″ _{j is} an appropriate number of divisions for defining a class for distinguishing traffic. At this time, 'what you direct sum divides _j q' q 'is denoted _{as'' j, λ '''} j: = ( name of the parameter j, q' and '' _j). A set based on λ ′ ″ _j and the empty set φ is set as a target SDP parameter partitioned set Λ.

Here, two specific examples of λ ′ ″ _j are shown.
(Example 1) When the bandwidth range (kb / s) is divided into 0, 0 to 100 or less, 100 to 1000 or less, 1000 to 10000 or less, 10000 to 100000 or less, or 100000 or more. Λ ''' _b = (bandwidth, {[0,0], (0,100], (100,1000], (1000,10000], (10000,100000], (100000, ∞)}) (kb / s)
(Example 2) Rtp payload type value range is divided into five categories: audio, video, audio-video,?, N / A (see IETF-REC 3551)
λ ''' _r = (Rtp_payload_type, {{0,1,2, ... 23}, {24,25, ..., 31,32,34}, {33}, {35,36, ..., 70,71,77,78, ..., 126,127}, {72, ..., 76})

(Procedure 3)
The set G ′ = Θ × Λ × Ω × Δ is defined.

(Procedure 4)
Since some methods do not include SDP parameters in the transmission data (According to IETF-RFC 2976,3261,3262,3265,3311,3428,3578,4488, MESSAGE, SUBSCRIBE, NOTIFY are applicable), φ∈Λ The elements of Λ other than are excluded from the set G ′ and defined as G ″. That is, when G ″: = {(θ, λ, ω, δ) ∈G ′ | θ = MESSAGE or SUBSCRIBE or NOTIFY, λ = φ}.

(Procedure 5)
The set G ″ is defined as a class set G that is obtained by appropriately performing direct sum division in performing traffic control.

As a result of the above (procedure 1) to (procedure 5), the definition content of the class is determined. An example of the contents of this definition is shown in FIG. 11, where the calling subscriber category, method type category, and SDP parameter category are divided into direct sums. Further, in FIG. 11, parameters for identifying the classes 1 to 8 are described. The definition content of the class is stored in the class definition storage unit 22 and the class definition storage unit 45 prepared in advance by the operation of an input means (keyboard or the like) (not shown) by the operator. Referenced when calculating the number of allocated calls x _{i, k, l} . If the class definitions are the same, either (Procedure 1) or (Procedure 2) may be executed first, or (Procedure 2) may be executed while performing (Procedure 4). Well, (Procedure 3) may be executed after (Procedure 4). That is, the order of the procedure described above is not limited.

≪SDP parameter representative value determination map≫
In one session start / change signal received by the call restriction session control apparatus l, a plurality of parameter values may be listed for some parameters j.
For example, when audio and video are mixedly included as MediaType values, these combinations are associated with one MediaType representative value “video” (see FIG. 10). This mapping information is stored in the SDP parameter representative value determination mapping storage unit 43 (see FIG. 5B). In addition, when MediaType has a plurality of values, the RTP Payload Type value is also determined for each of them. Therefore, the RTP Payload Type value designated for encoding “video” on the signal is set as the RTP Payload Type representative value.

In general, for attribute, MediaType, and bandwidth, one representative element is mapped from a plurality of parameter values. A map (hereinafter referred to as “SDP parameter representative value determination map”) h _j that associates one representative value with such a plurality of parameter values can be expressed as follows.
h _j : (λ ''' _j ) ^{| λ''' j |} → λ ''' _j
Here, | λ ′ ″ _j | is the number of elements of λ ′ ″ _j , and (λ ′ ″ _j ) ^{| λ ′ ″ j |} is | λ ′ ″ _j | Represents the direct product of _j .

Then, the SDP parameter representative value determination mapping storage unit 43 stores the SDP parameter representative value determination mapping h _j for each of j = attribute, MediaType, and bandwidth (since the number of elements of λ ′ ″ _j is at most finite, This can be implemented by storing in the SDP parameter representative value determination mapping storage unit 43 setting data for associating a representative element among the combinations of | λ ′ ″ _j |.

On the other hand, the RTP Payload Type value defines a value corresponding to the representative MediaType value as in the above example. That is, SDP parameter representative value mapping for RTP Payload Type
h _r : Range of MediaType → RTP Payload Type
h _r (h _m ((λ ′ ″ _m ) ^{| λ ′ ″ m |} )) = h _m ((λ ′ ″ _m ) ^{| λ ′ ″ m |} ) The RTP Payload Type value set in the same line is assumed (in the example of FIG. 10, this value is “96”).
In addition, when the call control session control device l identifies which class each signal of session start / change corresponds to, the representative value of each SDP parameter of the signal is used (see FIG. 11).

  An example of processing for identifying a corresponding class from the protocol header of the session start / change request from the classes stored in the class definition storage units 22 and 45 will be described with reference to FIG. The request example shown in FIG. 10 is an example showing a main part of a session start / change request using SIP. There is a sentence that starts with “INVITE (session participation request)” in the start line of the header part, a destination sentence in the message header, and a line feed that is used to indicate the end of the header part. Next, additional information transferred by the SIP message such as SDP is described in the message body. The first parameter immediately after “a =” is an attribute value, and FIG. 10 shows the case of sendrecv, rtpmap, and fmtp. However, this is merely an example, and there are other attribute values. . In FIG. 10, only valid lines are searched for which attribute value (eg, sendonly, recvonly, sendrecv) stored in the class definition storage unit is on the protocol header, and the corresponding attribute value (eg, sendrecv) is searched. Identify. In addition, the first parameter immediately after “m =” indicates the media type and shows an example in which audio and video are recorded. There are other MediaType values. In FIG. 10, audio and video MediaTypes are mixed, but the MediaType is determined by the SDP parameter representative value determination map stored in advance in the SDP parameter representative value determination map storage unit 43 (see FIG. 5B). Corresponds to the representative value “video”. When MediaType has a plurality of values, an RTP Payload Type value is also determined for each of them (SDP parameter representative value determination map for RTP Payload Type). In FIG. 10, the RTP Payload Type value designated for encoding the MediaType representative value “video” on the signal is set as the RTP Payload Type representative value by the SDP parameter representative value determination map regarding the RTP Payload Type. In FIG. 10, the second parameter after “b =” (the parameter immediately after the colon) is a bandwidth value, and is represented as “10000” in FIG. That is, it is understood that this corresponds to (1000, 10000) (over 1000 and under 10000) Note that the bandwidth values [0,0], (0,100], (100,1000], (1000,10000) shown in FIG. , (10000, 100000], (100000, ∞) are merely examples, and different section settings may be used.

(Modification)
In the above-described embodiment, as illustrated in FIG. 1, the traffic distribution calculation device 10 and the session control device 40 have been described as separate devices. In this modification, a traffic control system 60 having both the function of the call control session control device l (see FIG. 5B) and the function of the traffic distribution calculation device 10 (see FIG. 5A) is shown in FIG. Will be described.

  As shown in FIG. 12, the traffic control system 60 in the modified example includes the functions of the traffic distribution calculation device 10 shown in FIG. 5 (a) and the call restriction session control device 1 shown in FIG. 5 (b). Note that the functions of the traffic distribution calculation device 10 and the call restriction session control device l are as already described in the present embodiment, and thus detailed descriptions thereof are omitted. The traffic control system 60 can be used at the position of the session control device 40 shown in FIG. As described in the present embodiment, communication of a part of the traffic (priority allocation class) can be secured with priority.

  As described above, according to the traffic distribution calculation device 10 and the call restriction session control device 1 of the present embodiment, in the measurement cycle k> 1 (however, the measurement cycle k immediately after congestion detection is 0), the equation (1) As shown in MAX (··), since the larger of the initial number of allocated calls or the number of outgoing calls in the previous measurement period k−1 is selected, the outgoing call is always secured while the initial allocated number of calls is secured. It is possible to secure the number of allocated calls that matches the trend of the number of calls. Therefore, communication of a part of the traffic (priority allocation class) can be secured with priority. In addition, when a call in the priority allocation class becomes a regulation encounter, reconnection is performed in order from the lowest priority of the non-priority allocation class, and finally, a retry is performed to give priority to communication of the call. Run. This makes it possible to ensure the communication of some traffic preferentially during traffic congestion. Further, the class can be defined by any combination of the parameters of the SIP, SIMPLE method category set and SDP parameter category set, the calling subscriber category, and the emergency call category.

  Further, in the present embodiment, the processing of each part of the traffic allocation calculation device 10 (see FIG. 5A) and the processing of each part of the call restriction session control device l (see FIG. 5B) have been described. This processing may be realized by a program installed when the traffic allocation calculation device 10 and the call restriction session control device l are each realized by a computer. This program can be provided via a communication line, or can be distributed by writing in a computer-readable recording medium such as a CD-ROM.

DESCRIPTION OF SYMBOLS 10 Traffic allocation calculation apparatus 20 Allocation value determination part 21 Control parameter management part 22 Class definition storage part 23 Calculation part 25 Measurement data management part 26 Measurement data storage part 27 Session control apparatus instruction | indication part 30 Session control apparatus information storage part 31 By class Initial allocation call number storage unit 32 Processable call number storage unit 33 Normal class incoming traffic data storage unit 34 Normal class outgoing traffic data storage unit 40 Session control device 41 Call control unit 42 Data measurement unit 43 SDP parameter representative Value determination mapping storage unit 44 Priority order setting storage unit 45 Class definition storage unit 50 Congestion session control device 51 Call restriction control unit 60 Traffic control system 90 Terminal l Call restriction session control device (session control device on the call restriction side)

Claims (11)

Out of calls that are session start / change requests for requesting processing to the congested session control device, which is the congested session control device, at the time of congestion of any of the plurality of session control devices used for C-plane of the IP network, The number of connectable calls, which is the number of calls that can be processed by the congestion session control device, is defined as X, and the calls added to the congestion session control device are defined based on information included in the calls For each class i, based on traffic measurement periodically performed in the session control device 1 on the call control side, which is the session control device that receives a call directed to the congestion session control device, the measurement cycle k−1 The number of outgoing calls of class i belonging to the class set G calculated from the traffic measurement data is a _{i, k-1, l,} and is based on the number of outgoing calls a _{i, k-1, l} . Accordingly, the number of connectable calls X is allocated to the allocated number of calls x _{i, k,} ... For each class i in the next measurement period k, and the number of calls added to the congestion session control device of class i is set to x _{i, k. In the} traffic allocation calculation method used in the traffic allocation calculation device that limits the total number of calls accepted by the congestion session control device to the connectable call number X or less by restricting to be equal to or less than
The traffic allocation calculation device includes a calculation unit and a storage unit that stores the definition of the class,
The computing unit distributes the class i read from the storage unit into a priority distribution class that preferentially secures communication during congestion and a non-priority distribution class that preferentially secures communication during congestion, and the storage unit Read out the initial allocated number of calls s _i of a predetermined value for each class i from
When the measurement cycle k immediately after congestion detection is k = 0 and the measurement cycle k> 1,
Using the function g: (0, ∞) → (0, ∞) for the function g (z) ≦ 1 / z regarding z, the number of allocated calls x _{i, k,} of the class i of each priority allocation class in the measurement period k _· a _{x i, k, · = g} (R p) · MAX {s i, a i, k-1, ·} ·· formula (1)
As
The number of allocated calls x _{i, k, ·} of class i of each non-priority allocation class of measurement period k is _expressed as x _{i, k, ·} = (a _{i, k−1, //} Σ _{j∈non-priority allocation class set} a _{j, k-1, ・} ) ・ (1-g (R _p ) ・ R _p ) ・ X
..Formula (2)
A traffic distribution calculation method characterized by calculating as follows.
Where R _p = (Σ _{i∈priority allocation class set} MAX {s _i , a _{i, k−1,} }) / X, s _· = X, a _{i, k−1,} and x _{i, k ,} the midpoint _of, "-" is a dot notation, represents the sum of all of the outgoing call restriction side session control device l. When the measurement cycle k> 1, the calculation unit
The number of allocated calls x _{i, k, l} of class i in the measurement period k, which is allocated to the session control device l on the call control side,
x _{i, k, l} = (a _{i, k-1, l} / a _{i, k-1,.} ) x _{i, k,} ... (3)
The traffic allocation calculation method according to claim 1, wherein: The calculation unit reads the initial allocated call number s _i from the storage unit,
When the measurement cycle k = 1, the number of allocated calls x _{i, k,.}
xi _{, k} ,. = s _i .. Formula (4)
The traffic allocation calculation method according to claim 1 or 2, wherein:
However, s _· = X. When the measurement period k = 1, the arithmetic unit calculates the number of normal outgoing calls of class i belonging to the class set G calculated from the normal traffic measurement data u _{i, l} (class i, outgoing call restriction). Side session controller l) and based on the number of normal outgoing calls,
The number of allocated calls x _{i, k, l} of class i in the measurement period k, which is allocated to the session control device l on the call control side,
x _{i, k, l} = (u _{i, l} / u _{i ,.} ) x _{i, k,} ... (5)
The traffic distribution calculation method according to claim 1, wherein the traffic distribution calculation method is calculated as follows. The computing unit is
SIP (Session Initiation Protocol), SIMPLE (SIP for Instant Messaging and Presence Leveraging Extensions) methods included in outgoing calls, parameters of SDP (Session Description Protocol), calling subscriber classification, and emergency call classification The traffic allocation calculation method according to any one of claims 1 to 4, wherein the class is defined by a combination thereof. Session start / change request for requesting processing to the congested session control device, which is the congested session control device, when one of a plurality of session control devices used in the C-plane (call control signal plane) of the IP network is congested Hereinafter, the session start / change request is referred to as a call), and the number of connectable calls, which is the number of calls that can be processed by the congestion session control device, is X, and the call added to the congestion session control device is X. A call is performed in the session control device l on the call restriction side, which is the session control device that receives a call directed to the congestion session control device, for each class i defined based on information included in the call. Belonging to the class set G calculated from the traffic measurement data of the measurement cycle k−1 based on the traffic measurement performed automatically. The number of outgoing calls for class i a _{i, k-1, l} (class i, measuring period k-1, the session control unit l of the call regulation side) and, the originating call number a _i, the _{k-1, l} Based on this, the number of connectable calls X is allocated to the allocated number of calls x _{i, k,} ... For each class i in the next measurement period k, and the number of calls added to the congestion session controller of class i is set to x _{i, k. ,} by restricting it to so _below-, a traffic distribution calculating device for limiting the number of calls total said congestion session controller accepts below the connectable number of calls X,
The traffic measurement data is received from the session control apparatus on the call restriction side, accumulated, and notified of the number of outgoing calls to the distribution value determination unit described below, and the distribution call which is a calculation result of the distribution value determination unit A measurement data management unit for notifying the call control side session control device of the number,
The distribution value determination for receiving the traffic measurement data from the measurement data management unit and calculating the number of allocated calls by the traffic distribution calculation method according to any one of claims 1 to 5 based on the traffic measurement data. A traffic distribution calculating device. In the session control apparatus on the call restriction side for determining connection of a call based on the number of allocated calls x _{i, k, l} acquired from the traffic allocation calculation apparatus according to claim 6,
The session control device includes a call restriction unit that controls call restriction and a storage unit that stores a definition of a class defined based on information included in a call that is a session start / change request,
The call restriction unit is
Based on the acquired number of allocated calls x _{i, k, l} , as a result of determining whether communication of class i calls stored in the storage unit is to be ensured or restricted,
If a call to the priority allocation class is a regulatory encounter,
Reconnects in order from the lowest class of the priority of the non-priority allocation class to determine whether or not communication is possible, and the call that has encountered the restriction via the class determined to be able to communicate A session control device that executes a retry for communicating with priority. The session control device on the call restriction side is:
Means for measuring time, and means for performing call restriction using a call density value that is the number of calls per predetermined unit time based on the number of allocated calls received from the traffic distribution calculating device,
As the processing in the unrestricted class that does not perform call restriction, the following processes (81), (82), and (83) are performed in order,
(81) receiving an instruction for calculating a call density value for all classes from the traffic allocation calculation device;
(82) The total number of outgoing calls of all classes including the unregulated class is added from an initial value of 0,
(83) Determine whether the total number of outgoing calls is less than the call density value for all classes,
If the total number of outgoing calls is less than the call density value for all classes, return to (82) again.
If the total number of outgoing calls is not less than the call density value for all classes, the call will be a restricted encounter for all classes other than the unregulated class,
When the unit time of the call density ends, the process returns to (82) again to execute the processing in order,
8. The session control apparatus according to claim 7, wherein when the measurement cycle ends, the process returns to (81) and the processing is sequentially executed. The session control device on the call restriction side is:
Based on the SDP parameter representative value mapping for associating one representative value with a plurality of parameter values when there are a plurality of parameter values for the SDP parameters included in the received call, and the SDP parameters Remember the defined class,
9. The session control apparatus according to claim 7 or 8, wherein which class the received call corresponds to is determined using the SDP parameter representative value determination map.   A computer-readable recording medium storing a traffic control program for causing the traffic distribution calculating device as a computer to execute the traffic distribution calculating method according to any one of claims 1 to 5. 10. A computer-readable recording medium storing a session control program for causing a computer to function as the session control device on the call restriction side according to claim 7.

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